What's one thing you wish you could do in your lifetime, but you know you can't/won't be able to?

Whether it's because you don't have the money, life handed you one crap thing after another, or because someone/something is holding you back, I want to know if there's something you want to do, but just can't.

Everyone talks about their dreams and such, but I know there's people out there that are hindered from fulfilling them.